Forward Looking Sonar... Good to Have for Seeing Obstructions Ahead or Not?

[HighFly_27]

Hello All,

I'm doing a complete refit of my 1970 Islander 37 MS. The I-37 has outdated equipment and needs about everything. I'm going to be solo a lot and considering a Forward Looking Sonar (FLS) to detect obstructions ahead. I think the dead ahead range is around 150 to 200 feet for most of FLS's. I'm concerned about hitting submerged items in the water & solo and only one pair of eyes to spot things.

My old sonar (keel depth) is inoperative and needs replaced in the refit.

I'd like to hear from the folks that own or have operational experience on FLS's.

Are they a good investment ? I see them on EBay for around $ 900.00 to $ 1,100.00.

Thanks,

Avery

[skipmac]

Hi Avery,

A search on the forum will turn up several previous threads that have covered this in great detail, including reports from several users.

Short summary, at slow speed in calm water, like entering a channel or maneuvering around an uncharted harbor they do pretty well.

If you want something that will detect floating hazards at sea like a semi submerged shipping container then not really effective.

[fishbait58]

We are researching the same thing. Would love to hear what you decide on.


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[Terra Nova]

I think it's a gimmick.

[Roy M]

Often, it's the people that don't have something that decry the value of it to others. Seems to be working here, as well. I have an Interphase SE 200C. All forward looking sonars send out a beam. That beam has a range that is dependent on the depth of the water. In shallow water, about 25 feet (8 meters), my unit "sees" about 100+ feet. In deep water, about 1000 feet, it has the ability to identify targets near the surface for about 1000 feet forward, and a couple hundred feet below. For me, that is sufficient to give advance warning of a channel bank, a wreck or pinnacle, a school of bait, or a sleeping whale on the surface. It will also pick up deadheads (vertically floating, bobbing logs), but I haven't seen any yet. I normally use the unit in vertical mode to pick up targets ahead of me. It has an alarm, allowing me to switch over to the 180 degree (full beam to beam from course line) horizontal mode, which is handy should the target ahead prove to be a reef spanning my forward options. Newer forward looking sonars are coming to market, though the Garmin/Interphase unit seems to have hit a wall. The poop is that these newer units will have considerably greater resolution than the SE 200C. Mine is like a simple radar, but that's better than I had with no FLS, so I'm happy. Here's a picture of my two transducers, mounted on either side of my mini-keel. I also have a vertical sonar mounted just forward. There appears to be no issue operating them simultaneously, but normally I just use the FLS.

[Olde Chief]

Ahoy Crew, I can only give you my opinion, which is limited to years on the water. Fwd. looking sonar is a waste of money, unless you plan to do a lot of operation in shallow water at very slow speed, like in rivers and lakes near shore, where the bottom changes for various reasons, like flood debris and where people might dump things like stolen cars. Another reason I do not care for the idea is it put another hole in the hull below the water line, that is not needed. A question you might ask yourself is why doesn't the CG use Fwd looking sonar on their river and coastal patrol boats? You will probably have more fun spending the money on wine and other toys...

[skipmac]

Click on these links to read a few of the previous discussion and opinions from owners of these units.


http://www.cruisersforum.com/forums/...onar-8649.html

http://www.cruisersforum.com/forums/...ar-132087.html

http://www.cruisersforum.com/forums/...rs-102708.html

http://www.cruisersforum.com/forums/...ts-142160.html

http://www.cruisersforum.com/forums/...ar-124700.html


http://www.cruisersforum.com/forums/...ar-133039.html

[Terra Nova]

Notice it is generally brand new sailors that are inquiring about the use of these? It must seem like magic to them to be able to never ever worry again about a collision.

[exMaggieDrum]

Just for grins - some calculations on reaction times using FLS:

@ 5 kts you go 5x6000'/hr = 30,000'/hr or 500'/min or 8.3'/sec

so you it takes about 12 seconds to go 100', 24 seconds to go 200'

Don't know about your reaction times but I could in no way even start to do anything about an obstruction that just popped up on the sonar without warning before I hit it at that speed. Even if I were expecting something I couldn't slow the boat down enough to make much difference. Might be able to turn the boat if it were not very wide an obstruction. If it were a reef it would be all over.

I have been in a couple of situations trying to find a spot to anchor along the shore of a deep anchorage where I might have used a forward looking sonar but in reality I had no business trying to anchor in both situations.

In the Pacific NW we have a fair number of deadheads bobbing around. If one of these sonars could keep me from hitting one that could be useful but it would only work if you react immediately and can turn the boat before closing on it.

IMO they are not worth the money and give a false sense of security. But I wouldn't ridicule anyone who put one on either. To each his own.

[W3GAC]

I have an older Interphase. Used it for ten years in the Bahamas & Caribbean. But as most others have said it will paint a good forward look of the bottom while SLOWLY coming making landfall/ draw any channel so you can stay in the middle. But I emphasize... I HAD TO CREEP IN to allow the slow audio pings/ return reflections paint the pix. In a vertical sweep mode I could see the chain go down from a bouy... But as others have said, at least mine/ most don't have a shallow enough launch angle to see anything just below the surface ahead. With my 6' draft and usual sailing cruising speeds I would not be able to 'see' anything floating on/ just below the water surface. The things it did see ahead were deep enough that it would have been any any issue to go right over. In the end, because in the Bahamas/ Caribbean you can see the bottom coming in slowly, it got less and less use except when coming in with Sun in your face/ after dark/ heavy winds it was very useful in the left-right sweep mode to stay in center of channel.


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[adlib2]

Originally Posted by HighFly_27

Hello All,

I'm doing a complete refit of my 1970 Islander 37 MS. The I-37 has outdated equipment and needs about everything. I'm going to be solo a lot and considering a Forward Looking Sonar (FLS) to detect obstructions ahead. I think the dead ahead range is around 150 to 200 feet for most of FLS's. I'm concerned about hitting submerged items in the water & solo and only one pair of eyes to spot things.

My old sonar (keel depth) is inoperative and needs replaced in the refit.

I'd like to hear from the folks that own or have operational experience on FLS's.

Are they a good investment ? I see them on EBay for around $ 900.00 to $ 1,100.00.

Thanks,

Avery

I CONTACTED RAYMARINE A COUPLE OF YEARS AGO AS I WAS INTERESTED IN FLS. WHILE THEY MAKE THEM FOR LARGE VESSELS THE TRANSDUCERS ARE TOO LARGE FOR A RECREATIONAL SAILBOAT AND THEY DON'T RECOMMEND THEM. ALTHOUGH, THEY DID ADD THEY ARE TRYING TO DEVELOP SMALLER PRACTICAL TRANSDUCERS.

[Mycroft]

I agree that the FLS is probably not that valuable for dodging logs or containers. However, I think it would be very useful for navigating bays and looking for a suitable anchorage. What about navigating badly charted coral reef entrances to islands?

[oregoncycle]

Tossing out my 2 cents.I would think that this forum isn’t the right place to ask about these units as with the rapidly changing aspect of computers and electronics anyone whose sonar is over 1 year old cannot give a fair representation of what today’s sonar is capable of doing. Is this any different of what my 10 year old computer was capable of? For in its day it was amazing but now my phone has more capability then that 10 year old computer.
I would be talking directly to the makers of these sonars to get some fairly accurate information.

[Roy M]

Again, it would appear that those who don't use them seem to condemn them. Folks who do use them (Jim and Ann Cate for starters) appreciate them, despite whatever limitations their models may have. And the industry seems to agree that there is a future to the technology, as they are spending a lot of $$$$$ for R&D. And then there are those who don't believe in the value of stuff beyond their ken. It's human nature to believe what you want to believe, and to deride what you don't. Fortunately, not all of us think alike.

[bobnlesley]

...I see them on EBay for around $ 900.00 to $ 1,100.00...

Are they really that expensive? We have one on our boat - an 'Echopilot' - which other than turning on once in a blue moon, just to see if it still works, we've never used once used in anger; another of the silly 'toys' the last owner fitted: By pure chance, we used the same Surveyor when purchasing the boat, that he had four years before; we conservatively estimate that he'd spent in excess of £12,000/$18,000 dollars in those four years, including said echo-sounder, but had never got around to fixing the non-functioning manual bilge pump! He had fitted a pretty electric one though - it was job #1 on our list and took 30 minutes and cost nothing (a loose nut on the diaphragm's centre bolt). We're likely to be hauling out in a couple of months, so I'm going to check on the value cost of ours; if people are paying that sort of money for them, I'll take it out, fill the holes and you'll see it on ebay shortly.